Exogenous insulin in bodybuilding has many misapplications and misunderstandings brought about from lack of understanding of basic human endocrinology. If you ask around about insulin you will hear that insulin is the game changer for muscle growth, but careful it will make you fat. Also, make sure to cycle off so you don’t get insulin resistant. Then if you use HGH to make sure to use insulin to get the most out of it.
All of these statements are NOT accurate. I love to learn how things work and by doing so we gain better understanding on how to apply them. With more accurate approaches we can improve physique outcomes.
Insulin Makes You Huge!
Let’s start with the claim “exogenous insulin is the game changer for muscle growth”.
Insulin is an “anabolic” hormone, which simply means it promotes a “growth” environment. Insulin can shift metabolic pathways for storage and shuttling nutrients into cells, but this does not only mean muscle. It also means shifting storage into fat cells as well.
Simply stated, Insulin, opens the door via the insulin receptor to then shuttle in glucose and amino acids which then “turn on” protein synthesis and decrease protein degradation.
The question to ask is: Is there even an advantage to exogenous insulin if you have adequate endogenous production? I would argue NO.
Show Me The Proof
In the evidence based world one of the strongest lines of evidence comes from systematic reviews which is a comprehensive and rigorous analysis that synthesizes evidence from multiple studies on a particular topic. It involves systematically searching, appraising, and summarizing existing research to provide a comprehensive overview of the current evidence. We have a paper that does this regarding insulin and protein synthesis:
”Exogenous insulin does not increase muscle protein synthesis rate when administered systemically: a systematic review” (Trommelen, 2015)
This was a review of 40 papers and the conclusion was that it is the administration of amino acids that increase protein synthesis and insulin has a permissive role and not a contributory role in protein synthesis. Exogenous insulin failed to further augment protein synthesis during hyperaminoacidemia conditions.
In other words Insulin is the key that opens the door but amino acids go inside turn on the machinery. Now, is a research paper the end all be all? No, we should leverage our coaching experience as well. There are coaches at the top of the industry that never use insulin and some that do. Speaking to competitors with experience on the subject you will find that many have never seen the robust change in growth with it. The confounding variables for those that see a result is also that they concurrently pushed food and were more progressive with training at the time of insulin use, which as we know are the big ticket items to making a lot of progress.
Supraphysiological Dosing Insulin
We can NOT use supraphysiological doses of insulin like we can Human Growth Hormone (HGH) and anabolic steroids. Insulin use must be paired with carbohydrate intake or we would risk hypoglycemia, which can be very dangerous. Say you eat 100g of carbohydrates and to manage blood glucose this requires 10 units of insulin production by your pancreas. By taking 15 units of exogenous insulin this would lead to hypoglycemia and risk of death.
Testosterone differs in that it may produce 100 mg per week, but can inject 5x the amount and create a robust growth response. By increasing the insulin dose you must increase the carbohydrate amount and THIS is how guys end up getting fat on insulin. Insulin must be paired with the food intake, not pairing food to insulin usage. Back to the original point, exogenous insulin has limited advantage of endogenous production as they are one in the same for their role in managing blood glucose and the uptake of amino acids.
When to Use Exogenous Insulin?
Where we see a need for exogenous insulin is when challenging insulin production levels to that of diabetic ranges and this is seen in exogenous HGH usage at supra-physiological levels. Not only that, but the compounding effect of high food intake, body weight and PEDs can create a state of insulin resistance and put high demands on insulin production requirements.
However, adding in insulin is not the fix to insulin resistance, but does offer some advantages. Now, we should have in place strategies to maintain insulin sensitivity before it’s an issue to begin with. The will be based on nutrition, training, supplements and PEDs to keep insulin sensitivity high in our growth phases. Exogenous insulin has a role in specific scenarios for this level of bodybuilder and why we now have an entire lecture dedicated to this topic on J3 University.
Want to Learn More?
Check out our Level 1 J3 University Course HERE to learn all about our glucose management lecture and all teaching on physique enhancement.
References:
Trommelen J, Groen BB, Hamer HM, de Groot LC, van Loon LJ. MECHANISMS IN ENDOCRINOLOGY: Exogenous insulin does not increase muscle protein synthesis rate when administered systemically: a systematic review. Eur J Endocrinol. 2015 Jul;173(1):R25-34. doi: 10.1530/EJE-14-0902. Epub 2015 Feb 2. PMID: 25646407.
